Hi..... I just purchased a Tamron 17-50 non vc lens to use with my D90, I wanted to see what aperture you recommend for landscape pictures in CO with this lens? Thank you
There's honestly no hard and fast rule... it all depends on the depth of the scene you're working with, the detail and size of the foreground objects, etc... basically, it depends upon your vision for the shot. Most often, landscape shots benefit from the deep focus of small apertures. But not all landscape/nature shots are enormous, sweeping vistas... and sometimes an excessively deep focus achieved with a tiny aperture is not only over-kill, but can also produce a slightly degraded photograph as compared to one taken with a larger, more appropriate aperture for the depth of the actual scene.
Traditionally, deep landscapes usually get the low-ISO/small aperture approach as mentioned by Aaron. Smaller apertures mean great depth-of-field, so most all of the objects in the frame, from the foreground elements to the distant background elements, will be in focus. In many cases, this is ideal.
However, there's a trade-off in that small apertures will rob you of some measure of sharpness due to diffraction. So, if a certain shooting situation truly doesn't require a tiny aperture, then you'd be better of using a bigger aperture and retaining more sharpness. For example, in a relatively shallow landscape scene, you might achieve effective depth-of-field with an aperture of f/11 and get a considerably sharper shot.
With landscape photography, you've got to take a moment to assess any given scene and determine the proper balance between wide depth-of-field (the smaller the aperture, the great DOF) and sharpness at the focus point (sharpest apertures are generally between f/8 and f/11, falling off noticeably in sharpness at f/16 or so).
PS - I see now that alot of you guys beat me to these points while I was writing.